Scientists from the University of Athens drew this conclusion after studying dental pulp extracted from the teeth of three people found in a mass grave in Athens' Kerameikos cemetery.

The mass grave was first discovered in 1994 and was dated to about 430 B.C., the time of the plague.

At least 150 bodies had been thrown into the pit, the corpses piled in five layers with no soil between them.

"It was evident that they were buried irregularly, hastily, and without the death rituals of the time, almost in a state of panic," said Manolis Papagrigorakis, a professor at the University of Athens' School of Dentistry who lead the study.

The study appears in the current online version of the International Journal of Infectious Diseases.

Plague Result of War?

The mysterious disease struck during the Peloponnesian War between Athens and Sparta that lasted from 431 to 404 B.C. (map)

Researchers believe the plague may have been the result of a military strategy devised by the Athenians' leader, Pericles.

To counter an offensive by the Spartans, Pericles evacuated parts of the Athenian territory and sheltered its citizens behind Athens' fortifications.

Gathering tens of thousands of people in overcrowded and unsanitary conditions created the perfect atmosphere in which infectious disease could spread, researchers say.